Field of the Invention
The present invention relates to a device which improves the carts for building bridges forward progressive, aimed at improving the insertion of special pieces, which are embedded in the concrete, a structural part formed from the platform constituting the bridge.
Description of Related Art
In the construction of bridges it is common during the design for the incorporation of special pieces to be planned during the construction of the bridge which reinforce the structure of the bridge.
The concreting of a bridge is carried out in sections. Furthermore, in bridges of large dimensions, a cart is used which advances along the length of the bridge, being positioned in successive positions in order to carry out successive placements of concrete via the cited cart.
The cart serves to support the formworks which configure the form of the bridge and on which the concrete is poured in successive placements.
The installation of these special pieces during the implementation of the construction works is carried out in the following manner:                with the cart in a concreting position, the special pieces are positioned on the cart by means of a crane,        the cart is made to advance to the following concreting position but with the cart carrying said special pieces,        a new section is concreted with the cart positioned in the new position.        
These special pieces, given the reinforcing nature thereof, are pieces with very high weight (10, 15, 20 tons) such that the positioning operation of said special pieces on the cart and the subsequent advance of the cart for the concreting of a section of bridge with the piece on the cart is a very delicate and dangerous operation, firstly because the mere fact of a crane leaving the special pieces with their high weight on the cart is an operation which can cause significant damage to the advance system of the cart and secondly, because the cart should be moved, without being secured to the structure, forwards to the following position with the special pieces on the cited cart.